This invention relates generally to the conversion of heat to electricity and more particularly to a power converter for converting the earth's albedo, that is, the infrared radiation of the earth, to direct current (dc) power during day and/or night for use by high-altitude platforms for propulsion, sensors, or other power requirements.
Pivotal in the development of a high-altitude vehicle station keeping platform, has been the source of energy for night operation. During the day, a light-weight solar array can convert energy from the sun into power for operation in wind conditions. However, at night powered balloons have historically relied upon chemical storage batteries that are heavy despite attempts to introduce high energy density (.about.155 watt-hours/kg). Under most favorable conditions such batteries account for 60% of the payload. Thus, most high-altitude platforms depend upon solar arrays, chemical batteries, or depletable fuels for power sources. Solar arrays are expensive and operate under direct solar illumination, not in the earth's eclipse (night). Chemical batteries for night operation are heavy and have a limited lifetime. Depletable fuels (including gases) have a limited life application.
Overlooked in a search for a night energy source has been the earth's albedo which has plagued balloonists by heating balloons under undesirable conditions.